The present invention relate to a power device for an automotive vehicle, especially to a power device for an automotive vehicle interrupting an output circuit by a crash sensor and an interlock switch.
In a conventional power device for an automotive vehicle shown in FIG. 1, a crash sensor 22 and an interlock switch 21 turn an interlock relay 23 OFF from ON. When turned OFF from ON, the interlock relay 23 turns contactor 24, which is connected to an output circuit of a power source, to OFF from ON. The crash sensor 22 detects the impact when an automotive vehicle crashes, and turns the interlock relay 23 to OFF from ON. The output circuit of a power source is interrupted by detecting the impact of an automotive vehicle to improve safety at a crash. Since the power device for an automotive vehicle has many secondary batteries connected in series in order to output high power by a high voltage, an extremely high current flows if shorting of the output circuit of the power supply occurs at a crash. A large amount of current generates a large amount of Joule heat in a short time. Therefore, it is important to quickly interrupt a large amount of current at a crash for safety of an automotive vehicle.
Further, the interlock switch 21 is provided in the power device of FIG. 1. When a power device is repaired for example, the interlock switch 21 interrupts the output circuit to improve safety. In the power device, the output voltage is an extremely high direct voltage, and the interlock switch 21 interrupts the output circuit to prevent an electric shock during maintenance work, or the like. Accordingly, the interlock switch 21 is turned OFF from ON when manually operated for a repair of the power device, or when it is detected that a case is opened, for example. In the power device with the interlock switch 21, the output circuit is interrupted, so that it is possible to conduct work safely.
Furthermore, a delay circuit 27 is provided in such a conventional power device in order to prevent a malfunction of the interlock relay 23. The delay circuit 27 is provided between the interlock switch 21 and the interlock relay 23 so as not to turn the interlock relay 23 to OFF from ON by a momentary interrupting signal outputted from the interlock switch 21. The interlock switch 21 can momentarily output an interrupting signal, when chattering occurs caused by vibrations of an automotive vehicle etc. If the interlock relay 23 is turned to OFF from ON in this state, the contactor 24 is turned OFF even it is unnecessary to turn it OFF. If the contactor 24 is turned OFF, the output circuit of a power device is interrupted, so that an automotive vehicle cannot run normally. It is important to prevent the interlock relay 23 from being turned OFF from ON for a safety run, when it is unnecessary. To achieve this, the delay circuit 27 is provided.
However, the power device shown in FIG. 1 has the disadvantage that a contactor cannot be quickly turned to OFF from ON, when a crash sensor detects an impact. The reason is that a crash sensor turns the interlock relay OFF via a delay circuit, and the turned-OFF interlock relay turns the contactor OFF from ON. In order to prevent a malfunction of an interlock relay, the interrupting signal outputted from an interlock switch is delayed by a delay circuit, and then an interlock relay is turned OFF; however, when a crash sensor detects impact, it is necessary to interrupt an output circuit of a power device as soon as possible. Nevertheless, in the power device of FIG. 1, the time from detecting impact by a crash sensor to turning the conductor OFF is not only operation time (T1) of the conductor, but a longer time due to the addition of delay time (T2) of the delay circuit and operation time (T3) of the interlock relay, as shown in FIG. 2. Accordingly, it takes time similar to the time interrupting the output circuit by the interlock switch. For this reason, when the crash sensor detects impact, the output circuit cannot be quickly interrupted.
The present invention has been developed to solve the above problems. It is an important object of the present invention to provide a power device for an automotive vehicle, which can quickly interrupt an output circuit corresponding to an interrupting signal of a crash sensor and can slowly interrupt corresponding to an interrupting signal of an interlock switch, capable of interrupting an output circuit in ideal time corresponding to both of a crash sensor and an interlock switch.
The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings.